Prime minister-in-waiting Gordon Brown used a surprise trip to Iraq today to pledge that in future security and intelligence would be kept independent of the political process.Prime minister-in-waiting Gordon Brown used a surprise trip to Iraq today to pledge that in future security and intelligence would be kept "independent" of the political process.

In an attempt to draw a line under the erroneous weapons of mass destruction claims and the "dodgy dossier", Mr Brown said he had appointed the cabinet secretary, Sir Gus O'Donnell, to make sure that in future any intelligence material put in the public domain was properly verified and validated.

Mr Brown's trip came as the Tories used an opposition day debate to call for an independent inquiry into the Iraq war - a bid which may attract some support from anti-war MPs on Labour's backbenches.

As Mr Brown arrived in Baghdad for talks with the British military and the Iraqi prime minister, Nouri al-Maliki, he pledged to "learn the lessons" of the run-up to the conflict.He said he had asked Sir Gus to set in train a process to make sure security and intelligence analysis was kept "independent of the political process".

The chancellor - who will take over at No 10 on June 27 - said he wanted a bigger role for parliament's intelligence and security committee, and confirmed that MPs would get to vote on whether the country should go to war, except in the most exceptional circumstances.But he pointedly refused to backtrack on the original decision to go to war with Iraq, saying it was a collective cabinet decision."We made the decision. I take responsibility for that decision," he told reporters.Mr Brown had talks with Mr Maliki and met leading British and American military commanders.The prime minister-in-waiting told reporters: "I'm here to listen, to learn, to assess what's happening, to see what's happening with al-Qaida, to see what's happening in relation to Iran, to see what's happening to the sectarian conflicts, to see all the people on the ground and make an assessment of what's happening so I'm better informed.

"We have got armed forces who are doing an absolutely brilliant job. My first impressions are meeting people who just show a tremendous dedication and duty."But he added: "What I'm saying is: we have lessons to be learned for the future."I have already said parliament should have a more formal role in issues of war and peace but I think we can go further and learn from what's happened over the last few years."I would like to see all security and intelligence analysis independent of the political process and I have asked the cabinet secretary to do that."

Mr Brown, like Downing Street, refused the Tory calls for an inquiry, saying: "The wrong time to even consider an inquiry is when you have to give all your effort to consider your troops on the ground."

He added: "I think it's important to learn all the lessons, just as Tony Blair has said he acted in good faith but mistakes were made. I think it's important to learn the lessons to look forward now."In fact, the Tory debate in the Commons does not put a timetable on an inquiry, it merely commits to one in principle.Mr Brown also refused to speculate on any timescale for the withdrawal of the remaining 5,500 UK troops in Iraq. He said in his talks with Mr Maliki that he had also discussed rebuilding Iraq's economy, saying: "I think the issue in Iraq is this: how can we help the Iraqi people not only run their own security and build a democracy but offer a prosperity they are perfectly capable of doing?"

Mr Brown stressed the UK had made commitments and promises both to the Iraqi people and the United Nations, adding: "This is not the right time to talk about [troop] numbers. I don't want to get into talking about timetables or numbers."

Mr Brown is also having talks today with the Iraqi president, the US ambassador, Ryan Crocker, and the American commander of the multinational force in Iraq, General David Petraeus.In London, Downing Street rejected Tory calls for a postmortem into the war, along the lines of the Franks inquiry into the Falklands war 25 years ago, saying: "Anything that diverts from the energy, the commitment, the focus in trying to get the situation right we believe is a distraction."There has already been an inquiry by the foreign affairs select committee, an inquiry by the security and intelligence committee, Lord Hutton's inquiry into the death of David Kelly and Lord Butler's inquiry into intelligence failures regarding weapons of mass destruction.In November 2006, the Scottish National party and Plaid Cymru tabled a motion for an immediate inquiry. But MPs rejected the move after a vote.

Both nationalist parties also backed a campaign for Mr Blair to be impeached, over accusations that he agreed with George Bush at a summit in Crawford, Texas to back the Iraq war, well before putting the case to the British public in two dossiers. "